1. Field of the Invention
The present invention relates to, for example, an apparatus, a method and a recording medium storing the method for distributing map information to one or plural mobile terminals through radio communication.
2. Description of the Related Art
Related Art 1
FIG. 13 is a block diagram showing a function of a conventional deformed map forming apparatus and a map information providing system using the deformed map disclosed in the Japanese Unexamined Patent Publication No. HEI 10-74042.
The deformed map forming apparatus includes a target relating means 106 and deformation means 107 through 112. The target relating means 106 relates information of a certain target stored in vector map data 101, which stores information of outline of targets and roads, to roads around the target so that the information of the target can be moved according to the transition of the road. The deformation means 107 through 112 perform deformation process of map data in which a target is related to roads by the target relating means. Since the target is related to the roads, a relationship among the target and the roads can be kept even if the map is deformed.
In the deformed map forming apparatus, the following means are provided as the deformation means: a route extracting means extracting only area along the searched route; a target neighborhood reforming means reforming the map of the neighborhood of a certain target by making a road around the target of the map longer so as to prevent the target from being overlapped by another target; a non-target neighborhood reforming means omitting road data which has no relation with the target; an angle modifying means modifying an angle at which lines cross each other; a crossing point moving means moving a consisting point of a line to a crossing point of meshes of the vector map; a straight line adjusting means adjusting a line to a straight line connected with the crossing point of meshes of the vector map; a map area setting means dynamically determining an extracting area of map according to the number of target; a road omitting means omitting road narrower than a predetermined width; another straight line adjusting means adjusting to a straight line two lines which cross each other by a small angle; a road shortening means shortening a long straight road; and a target omitting means omitting a target from the map area so that targets should not be overlapped. The deformed map forming apparatus regards relative relationship of the location and readability more important than the precision of the location. The apparatus focuses a map into an area along the searched route and the roads related to the area are deformed, and the apparatus omits a road which is not related to the target so as to simplify the map. When targets are overlapped, some of the targets are omitted according to a priority for displaying the targets.
Further, the map information providing system is configured by a portable terminal which is small, light and having radio communication function and an information provider providing such as map information in response to a search request from the portable terminal. The information provider includes a searching means consisting of an information storage area storing the map information, a searching means searching necessary information from the information storage area, the deformed map forming apparatus automatically generating the deformed map by simplifying the map information searched by the searching means, a communication means communicating with the portable terminal by radio, and a search controlling means analyzing the search request received via the communication means, generating a search command sequence for the searching means, transmitting the map information searched by the searching means to the deformed map forming apparatus, and transmitting the deformed map drawn by the deformed map forming apparatus to the portable terminal via the communication means.
The map information providing system reduces an amount of data by deforming the map so that the system enables:
1) to display readable map even on a display of small portable terminal with small display size, small capacity of memory, small capacity of disk and so on; and PA0 2) to distribute the map information to the portable terminal easily via the radio communication function having low and unstable communication performance. PA0 1) When communication infra structure (communication media) used for distributing the map is changed, an amount of data transmitted within a time is also changed because performance/characteristics of each communication media, namely, the communication speed and the communication band is different for each communication media. Accordingly, it is impossible to draw/modify the deformed map dynamically adaptable to the performance of various communication media. PA0 2) Further, since the deformation of the map reacting dynamically to traffic status of the communication media cannot be performed, a throughput of the network is much reduced once the traffic is congested. Therefore, the reduction of the throughput defects the map distribution service, for example, the distributing speed of the map is extremely decreased. On the other hand, when the deformation of the map is performed previously assuming the traffic status of the network, the apparatus cannot change to increase the precision of the map to be displayed even if the network traffic becomes low, which fails to satisfy the user. PA0 3) Yet further, since the map data is distributed through the channel with a low communication speed and a narrow communication band, it is impossible to transmit efficiently a large amount of map data.
Related Art 2
FIG. 14 shows a block diagram showing a function of a conventional graphic data managing apparatus consisting of a layered data structure disclosed in the Japanese Unexamined Patent Publication No. HEI 11-120330.
In the graphic data managing apparatus, on managing the graphic data to be displayed with overlaying figures on each layer, the layers are classified based on the attribute information assigned to each graphic data, which enables to easily and rapidly move the figure from one layer to the other layer corresponding to the change of attribute information when the attribution of the figure is changed.